Apparatus for the single withdrawal of articles in sheet form from a stack

ABSTRACT

This invention relates to an apparatus for the single withdrawal of articles in sheet form from a stack, especially for picture postcard vending machines, having a suction device connected to a vacuum pump and movable to and fro in the direction of the stack and a drive device for the advance and withdrawal of the suction device.

United States Patent Leiser Feb. 18, 1975 1 1 APPARATUS FOR THE SINGLE[56] References Cited WITHDRAWAL OF ARTICLES IN SHEET UNITED STATESPATENTS FORM FROM A STACK 3,411,640 11/1968 Wallis 214/85 D [75]Inventor: Hermann Leiser, Lohn, Switzerland 3,690,477 9/1972 Nilsson214/85 D X [73] Assignee: Strausak AG, Lohn, Switzerland PrimaryExaminerRobert J. Spar [22] 1'116C1I June 6, 1972 AssistantExaminerGe0rge F. Abraham Appl. NO.Z 260,095

Foreign Application Priority Data June 11, 1971 Switzerland 8493/71 US.Cl 214/85 1), 271/91, 271/106, 294/65 lm. c1. 865g 59/04 Field of Search214/85 D, 1 BT; 294/64 R, 294/65; 271/26 E, 30 A, 31, 32, 106, 102, 91

[57] ABSTRACT This invention relates to an apparatus for the singlewithdrawal of articles in sheet form from a stack, especially forpicture postcard vending machines, having a suction device connected toa vacuum pump and movable to and fro in the direction of the stack and adrive device for the advance and withdrawal of the suction device.

4 Claims, 5 Drawing Figures PHENTEU FEB] 8 $5. 5

APPARATUS FOR THE SINGLE WITHDRAWAL OF ARTICLES IN SHEET FORM FROM ASTACK BRIEF SUMMARY OF THE INVENTION Known withdrawal devices of thiskind possess the disadvantage that in the vertical removal of articlesof sheet form from a stack, several articles are often taken at the sametime. In the case of picture postcard vending machines, variousinconveniences can thus occur, in that for example the cards taken inexcess are also dispensed without the purchaser making payment for them,or they take a path not intended for them in the apparatus, so thatoperation stoppages can occur. In every case the economy of the vendingmachine is thereby rendered dubious.

In the case of a vertically arranged card stack in fact according to aknown proposal the possibility exists of curving the card to be takenfrom the top of the stack, during the withdrawal movement, so that anyfurther cards adhering to this card are detached and drop back on to thestack. Of course this solution fails in the case of any otherarrangement, for example horizontal, of the card stack.

The invention has the purpose of providing a with drawal device of theinitially stated kind in which single withdrawal is guaranteed and whichoperates satisfactorily with the stack in any position.

The apparatus according to the invention is characterised in that thesuction device comprises two suction cups which are so arranged inrelation to the stack that the first suction cup comes to act in themiddle part and the second suction cup comes to act on the margin of thearticle of sheet form to be taken in each case, and that the driveconnection with the first suction cup includes an idle motion so that atthe beginning of the retraction of the suction device in the withdrawalmovement direction the second suction cup is retracted alone at first,in order to lift the marginal region of the article of sheet form awayfrom the stack before its withdrawal.

As a result of this marginal lifting air can enter from the marginbetween the article of sheet form to be lifted away and the next articlewhich has to remain on the stack, so that in the subsequent withdrawalof the former adhesion of further copies is avoided.

BRIEF DESCRIPTION OF THE DRAWING The invention will be explained ingreater detail hereinafter by reference to an example of a form ofembodiment of the object thereof which is illustrated in theaccompanying drawing, wherein:

FIG. 1 shows a lateral elevation of the withdrawal apparatus and of acard stack from which the cards are to be taken singly;

FIG. 2 shows a lateral elevation of the suction device in anintermediate position during the withdrawal movement;

FIG. 3 shows a front elevation of the suction device;

FIGS. 4 and 5 show different positions of the valves provided for thecontrol of the drive device.

DETAILED DESCRIPTION OF THE INVENTION The apparatus as shown in thedrawings serves in the present example to take cards singly from thecard stack 1. The card stack 1 is situated in a card magazine forexample of a picture postcard vending machine which comprises a bottomrail 2 and a transparent front plate 3. The card stack 1 is heldtogether by two resilient curved retaining arms 4 pressing upon themarginal regions ofthe cards, one of which arms is visible in FIG. 1,these arms being secured on the bottom rail 2 of a further card magazine(not shown) situated thereabove.

The withdrawal apparatus comprises a suction device 5 whichcan be movedto and fro in the stack direction and a drive device 6, represented onlydiagrammatically in the drawing, for the advance and retraction of thesuction device 5.

The suction device 5 comprises two suction cups 7 and 8 which are soarranged in relation to the card stack 1 that the first suction cup 7comes to act in the middle part and the second cup 8 comes to act on thelower margin of the card to be taken in each case. The suction device 5is connected with a longitudinally movably guided drive rod 9 which isarranged coaxially with the first suction cup 7 and comprises a passage10 serving as suction conduit. The second suction cup 8 is seated, withaxis parallel to the drive rod 9, on a crosscarrier 11 firmly connectedwith the latter, and the first suction cup 7 is seated on a pivot arm 13which is articulated to the cross-carrier Mat 12 and is movable in theplane determined by the axes of the suction cups 7, 8. The pivotingrange of the pivot arm 13 is limited on the one hand by the front of thecross-carrier 11 and on the other by a stop 14 fitted on the pivot armand'cooperating with a cam 15 on the cross-carrier 11. A flexure spring16 presses the pivot arm 13 against the stack end of the pivoting range.This pivoting range forms an idle motion in the drive connection to thefirst suction cup 7, which takes effect in the retraction of the driverod 9 in a manner as described hereinafter. From the passage 10 in thedrive rod 9 a passage 17 in the crosscarrier 11 leads to the secondsuction cup 8, and through a branch passage 18, which is formedpartially by a flexible pipe 19 (FIG. 3), the first suction cup 7 isalso connected with the suction conduit.

The drive device 6 comprises a working cylinder 20 with double-actingpiston 21, the piston 21 being connected with the drive rod 9 on itsfront, facing in the direction of advance (arrow 22 in FIG. 1). Thesuction conduit formed by the passage 10 in the drive rod 9 opensthrough a passage 23 in the piston 21 into the cylinder chamber 24 onthe rear of the piston 21. The forward cylinder chamber 25 and the rearcylinder chamber 24 are connectable with a vacuum pump 28 throughprogram-controlled valves 26 and 27. The suction generated during thewithdrawal operation by the vacuum pump 28 is effective both in theworking cylinder 20 and through the suction conduit in the suction cups7, 8. A tension spring 29 arranged in the forward cylinder chamber 25and acting on the piston 21 serves for the advance of the suction device5.

On the cross-carrier 11 of the suction device 5 a detent disc 30 isseated on the drive rod 9, by means of which disc the suction device 5is held in its rearward rest position (position of the detent disc 30entered in dot-and-dash lines), namely by a pawl 31 which is released onenergisation of an electromagnet 32.

The manner of operation of the apparatus as described is as follows:

On release of the pawl 31 the suction device 5 moves under the action ofthe tensioned spring 29 in the direction of advance indicated by thearrow 22 against the card stack 1 into the working position asrepresented in FIG. 1. In this working phase the vacuum pump 28 is notyet in operation. The suction cup 8 is pressed by the force of thespring 29, through the cross-carrier 11, and the suction cup 7 is alsopressed by the force of the flexure spring 16 acting upon the pivot arm13, against the foremost card 33 of the card stack 1.

Now the vacuum pump 28 is set in operation, whereby the retraction ofthe suction device 5 in the withdrawal movement direction commences(arrow 34 in FIG. 2). The valves 26 and 27 assume in the firstretraction phase the position as illustrated in FIG. 1, so that thus thetwo cylinder chambers 24 and 25 of the working cylinder and, from thecylinder chamber 24 on the rear of the piston, through the passages 23,10, I7 and 18, the two suction cups 7 and 8 are connected with thevacuum pump 28. Firstly thus the foremost card 33 of the card stack 1 issucked fast on to the suction cups 7, 8 of the suction device 5.Furthermore the piston 21 begins to move in the withdrawal movementdirection (arrow 34 in FIG. 2). In this movement, the differential forcederiving from the different sizes of the piston areas on the two sidesand the force of the nearly relaxed tension spring 29 act upon thepiston 21, the force of the tension spring 29 in this condition beingdimensioned so that in this first return phase a resultant force isexerted in the withdrawal movement direction upon the suction device 5.The initially relatively slight retraction force has the effect that thesuction device begins to move slowly, which has a favorable effect uponthe operation as described hereinafter in the first retraction phase.

During the first retraction phase the first suction cup 7 continues topress the card 33 to be withdrawn upon the card stack 1, under theaction of the flexure spring 16, as a result of the idle motion in thedrive connection to the first suction cup. The second suction cup 8,which is rigidly connected with the drive rod 9 through thecross-carrier 11 and acts upon thelower margin of the card 33 is thusinitially retracted alone. Thus before the withdrawal of the card 33 itslower margin is lifted away from the card stack 1 according to FIG. 2,so that air can enter from the card edge (in the direction of the arrow35) between the card 33 to be withdrawn and the next succeeding card ofthe card stack 1.

As soon as the stop 14 has reached the dog 15, that is at the end of theidle motion, the first cup 7 is also operatively connected with thedrive device 6. Now the second retraction phase commences in which withthe withdrawal movement continuing the first suction cup 7 acting in themiddle part of the card 33 draws this card off from the card stack 1,the card 33 being easily detached from the next succeeding card of thecard stack l, which detachment is favored by the access of air to theback of the card. Approximately at the transition from the first to thesecond retraction phase the valve 27 is rotated into the position asshown in FIG. 4, while the position of the valve 26 remains unchanged,so that now only the cylinder chamber 24 on the rear of the piston ofthe working cylinder 20 is connected with the vacuum pump 28. Thus, theretraction force and thus the retraction speed are increased. Now thelateral edges of the card 33 are drawn forward under the curvedretaining arms 4.

As soon as the suction device 5, with the card 33 held fast on it bysuction, has reached its rest position again at the end of theretraction movement, the pawl 31 places itself before the detent disc30, whereby the withdrawal operation is terminated. Then the valves 26and 27 are rotated into the position as shown in FIG. 5, whereby thesuction effect is interrupted and the card 33 detaches itself from thesuction cups 7, 8 and drops into a delivery shaft (not shown).

As long as the vacuum pump 28 continues in operation for a specifictime, air is blown into the forwardcylinder chamber 25 of the workingcylinder 20, which however has no effect in this operational case.

When the card stack 1 is consumed and the suction device 5 encountersthe front plate 3 of the card magazine, firstly the suction cups, 7, 8adhere firmly by suction to the front plate 3 and the retraction phasesas described above do not take place. However as soon as the programcontrol system effects the rotation of the valves 26, 27 into theposition as shown in FIG. 5, the suction effect disappears so that thesuction cups 7, 8 disengage from the front plate 3 and the suctiondevice 5 is moved back into its rest position against the force of thetension spring 29 under the action of the air blown by the vacuum pump28 into the forward cylinder chamber 25 of the working cylinder 20.

Of course it is possible for several suction devices, connected with onecommon drive device, to be provided for the withdrawal of largerarticles of sheet form.

What we claim is:

1. An apparatus for the single withdrawal of articles of sheet from astack, especially for picture postcard vending machines, having asuction device connected to a vacuum pump and movable to and fro in thedirection of the stack and a drive device for the advance and retractionof the suction device, characterized in that:

the suction drive comprises two suction cups which are so arranged inrelation to the stack that the first suction cup comes to act in themiddle part and the second cup comes to act adjacent the edge of thearticle of sheet to be withdrawn, and in that the drive device includesa longitudinally movable guided drive rod; and in that the suctiondevice includes a cross-carrier connected to an end of the drive rod andextending transversely from the drive rod, a pivot arm pivotallyconnected to the cross-carrier and movable in a plane determined by theaxes of the suction cups, stops limiting the pivoting range of the pivotarm, and a spring connected to the cross-carrier and the pivot arm forpressing the pivot arm toward the stack end of the pivoting range, thefirst suction cup being located on the pivot rod substantially incoaxial alignment with the drive rod, and the second suction cup beinglocated adjacent the pivotal connection of the cross-carrier to thepivot arm, the axis of the second suction cup-being parallel to thedrive rod, whereby the drive device is operatively connected to thesuction device to provide a limited amount of idle motion between thedrive device and the first cup during the beginning of the retraction ofthe suction device in the withdrawal movement direction, so that thesecond suction cup is firstly retracted alone, thus lifting the edge ofthe article of sheet form away from the stack before its withdrawal.

2. An apparatus according to claim 1, characterized in that theretraction force exerted upon the suction device by the drive device atthe beginning of the withdrawal movement is less during the singlemovement of cylinder chamber on the rear of the piston, further in thatthe two cylinder chambers are connectable with the vacuum pump throughprogram controlled valves and in that the controlling of the valves forthe retraction of the piston and thus of the suction device is arrangedin i such a way that in a first retraction phase at the beginning of thewithdrawal movement of the suction device the two cylinder chambers areconnected with the vacuum pump and in a subsequent second retractionphase only the cylinder chamber to the rear of the piston is connectedwith the vacuum pump.

4. An' apparatus according to claim 3, characterized in that for theadvance of the suction device there is provided a balance spring whoseforce is dimensioned so that in the first retraction phase a resultantforce is exerted in the withdrawal movement direction upon the suctiondevice.

1. An apparatus for the single withdrawal of articles of sheet from astack, especially for picture postcard vending machines, having asuction device connected to a vacuum pump and movable to and fro in thedirection of the stack and a drive device for the advance and retractionof the suction device, characterized in that: the suction drivecomprises two suction cups which are so arranged in relation to thestack that the first suction cup comes to act in the middle part and thesecond cup comes to act adjacent the edge of the article of sheet to bewithdrawn, and in that the drive device includes a longitudinallymovable guided drive rod; and in that the suction device includes across-carrier connected to an end of the drive rod and extendingtransversely from the drive rod, a pivot arm pivotally connected to thecross-carrier and movable in a plane determined by the axes of thesuction cups, stops limiting the pivoting range of the pivot arm, and aspring connected to the cross-carrier and the pivot arm for pressing thepivot arm toward the stack end of the pivoting range, the first suctioncup being located on the pivot rod substantially in coaxial alignmentwith the drive rod, and the second suction cup being located adjacentthe pivotal connection of the cross-carrier to the pivot arm, the axisof the second suction cup being parallel to the drive rod, whereby thedrive device is operatively connected to the suction device to provide alimited amount of idle motion between the drive device and the first cupduring the beginning of the retraction of the suction device in thewithdrawal movement direction, so that the second suction cup is firstlyretracted alone, thus lifting the edge of the article of sheet form awayfrom the stack before its withdrawal.
 2. An apparatus according to claim1, characterized in that the retraction force exerted upon the suctiondevice by the drive device at the beginning of the withdrawal movementis less during the single movement of the second suction cup than afterthe commencement of the action of the force upon the first suction cup.3. An apparatus according to claim 1 characterized in that the drivedevice comprises a working cylinder with double-acting piston, thepiston being connected with the drive rod on its forward side facing inthe direction of advance, while a suction conduit connected with thesuction cups and formed by a passage in the drive rod opens through apassage in the piston into the cylinder chamber on the rear of thepiston, further in that the two cylinder chambers are connectable withthe vacuum pump through program controlled valves and in that thecontrolling of the valves for the retraction of the piston and thus ofthe suction device is arranged in such a way that in a first retractionphase at the beginning of the withdrawal movement of the suction devicethe two cylinder chambers are connected with the vacuum pump and in asubsequent second retraction phase only the cylinder chamber to the rearof the piston is connected with the vacuum pump.
 4. An apparatusaccording to claim 3, characterized in that for the advance of thesuction device there is provided a balance spring whose force isdimensioned so that in the first retraction phase a resultant force isexerted in the withdrawal movement direction upon the suction device.